Traceable Frangible Projectile

ABSTRACT

A frangible projectile useful in a round of gun ammunition wherein, upon striking a target, the projectile selectively disintegrates, leaving intact at least one portion or appurtenance of the projectile which is recoverable for purpose of identification of rifling markings thereon and/or other analysis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/949,101; filed Jul. 11, 2007.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

FIELD OF INVENTION

This invention relates to the tracing of a spent bullet (projectile) to the gun from which the projectile was fired. More particularly, this invention relates to the traceability of a frangible projectile to the gun from which such frangible projectile was fired.

BACKGROUND OF INVENTION

Traceability of a spent projectile to the gun from which it was fired is a major factor in criminology. Commonly a projectile designed to be fired from a gun comprises a soft metal jacket housing a frangible core. When such projectile is fired from a gun having a rifled barrel, the rifling internal of the barrel imparts a “signature” to the outer surface of the jacket as the projectile moves through and out of the barrel. In a fully frangible projectile, as opposed to a fragmenting projectile, there commonly is no part of the projectile which is recoverable and useful as enables a criminologist to identify any markings on the jacket which might be valuable in identifying the gun from which the projectile was fired.

Of recent, there has been introduced to the marketplace a projectile 10, FIG. 1, which when fired from a gun having a rifled barrel, will disintegrate into minute particulates. Commonly, such projectiles are designed to “fully” disintegrate, including the jacket itself, when the projectile strikes a solid, semi-solid or hydraulic (animal) target so that none of the minute particulates exhibits identifiable markings thereon which were imparted to the projectile during its course through and out of the rifled barrel.

Referring to FIG. 1, one such frangible projectile comprises a cup-shaped metal jacket 12 having a closed trailing end 14 and an open leading end 16. This jacket houses therein a core 18 formed from at least one, and more commonly, a blend of two or more metal powders 20. In one embodiment, the core of this frangible projectile is compacted in a die at room temperature to define a self-supporting compact (core). Most commonly, one such core is disposed within the jacket and the leading end of the jacket is closed, at least to the extent required to retain the core within the jacket prior to any firing of the projectile from a gun. Commonly, the closing of the jacket and core includes formation of an ogive 22 on the leading end of the projectile.

Upon a frangible projectile as described above and depicted in FIG. 1, striking a solid, semi-solid or hydraulic target, both the jacket and the core disintegrate into individual particulates which are substantially useless for purposes of attempting to trace the bullet back to the gun which fired the projectile. This frangibility feature of the projectile is useful and desirable for establishing limited penetration into a target enhanced destructive capability, and/or prevention of undesirable ricochet of the projectile and accompanying unacceptable collateral damage, particularly injury or death of an unintended target, such as innocent bystanders.

Ammunition comprising frangible projectiles also are desirable in that they do not contain undesirable lead metal. In certain quarters, this ammunition is termed “green” ammunition in that it does not introduce lead to the environment. In particular, the ammunition which employs these frangible projectiles is desired by both military and civilian defense forces for the reasons, among others, that once the projectile strikes a solid or hydraulic target (such an animal or human being), the fast spinning projectile substantially disintegrates into minute individual particulates which either do not exit the target, or if they do exit the target, their momentum very quickly reduces to a harmless velocity. Due to their frangibility, these projectiles do not ricochet at approach angles as small as about 15 degrees.

However, these fully frangible projectiles do not leave intact any portion of the projectile which is useful for identifying rifling markings thereon, if any.

SUMMARY OF INVENTION

According to one aspect of the present invention, the present inventor provides a frangible projectile useful in a round of gun ammunition wherein, upon striking a target, the projectile selectively disintegrates, leaving intact at least one portion or appurtenance of the projectile which is recoverable for purpose of identification of rifling markings thereon and/or other analysis thereof.

In one aspect of the present invention, the inventor provides for structuring the projectile to include a disintegration-limiter factor which establishes selective disintegration of the projectile when the fired projectile strikes a target, while also providing for a selected portion of the projectile bearing rifling marking to remain intact upon striking the target. This structuring of the projectile may take the form of structural design of the jacket in the region thereof most adjacent the trailing end thereof or, in another embodiment, it may take the form of incorporation into the projectile of an appurtenance which takes on indentifying rifling marking as the projectile passes through the rifled barrel of a gun and which survives intact upon disintegration of the core upon the projectile striking a target.

The disintegration-limiting factor may take on several forms, but in each form, the projectile is designed to disintegrate upon striking a target, such disintegration commencing at the leading end of the projectile and promulgating toward the trailing end of the projectile. Such limiter factor may be formed integrally of the jacket and/or may be in the form of an appurtenance supplied to the frangible core of the projectile. Such limiter factor effectively either retards or halts the promulgation of disintegration of the core and resultant intact survival of at least an appurtenance or a portion of the projectile disposed proximate the trailing end of the projectile, resulting in preservation of an intact recoverable portion of the projectile having rifling markings thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional representation of a frangible projectile of the prior art;

FIG. 2 is a schematic sectional representation of one embodiment of a projectile embodying various features of the present invention;

FIG. 3 is a schematic sectional representation of a further embodiment of a projectile embodying various features of the present invention;

FIG. 4 is a schematic sectional representation of one embodiment of a dual-core projectile embodying various features of the present invention;

FIG. 5 is a schematic sectional representation of a still further single-core embodiment of a projectile embodying various features of the present invention;

FIG. 6 is a schematic sectional representation of a further embodiment of a dual-core projectile embodying various features of the present invention;

FIG. 7 is a schematic sectional representation of a still further embodiment of a dual-core projectile embodying various features of the present invention;

FIG. 8 is a schematic sectional representation of an embodiment of a multi-core projectile as depicted in FIG. 7 which employs strips of soft metal affixed to the outer surface of the cores;

FIG. 9 is a side elevational representation of a round of ammunition including one embodiment of a projectile of the present invention;

FIG. 10 is a schematic representation of an enlarged portion of a projectile of the present invention as recovered intact from a target and depicting rifling marking thereon;

FIG. 11 is a representation of a typical gel block into which a frangible projectile of the present invention has been fired and depicting a typical dispersion of the disintegrated particulates of the projectile when it strikes the gel block; and,

FIG. 12 is a schematic sectional representation of a single-core embodiment of a projectile as depicted in FIG. 5 but including a disc embedded within the core and embodying various features of the present invention

DETAILED DESCRIPTION OF THE INVENTION

In accordance with one aspect of the present invention there is provided a round of ammunition 11 comprising a projectile 10 (see FIG. 1) embodying various of the features of the present invention. To this end, the projectile includes a cup-shaped jacket 12 is formed from a relatively soft metal, such as brass or copper, Internally of this jacket there is disposed a frangible core 18 formed of at least one, and preferably a mixture of metal powders 20. Suitable metal powders are known in the art, and include powdered heavy metals such as tungsten, uranium, tantalum and like metals, and powdered lighter metals such as tin, copper, zinc and like metals. Other powders may be employed, such as carbides of the heavy metal powders or alloys of two or more of the metal powders. In certain applications, the powder from which the core is formed may be a non-metal. Most commonly, the core is formed from a blend of powders which is die formed into a self-supporting compact, preferably at about room temperature and forming pressures, e.g. between a few hundred psi and multiple thousands psi, depending in part upon the intended product and the powders employed. The percentage of each powder included within a blend of powders may range from about 1 percent to about 99 percent, by weight of the overall weight of the blend of powders. In certain applications, it may be desired to utilize a single powder. In one embodiment, prior to loading a powder blend into a die cavity, there may be added to the blend a matrix powder, such as micronized oxidized polyethylene powder. This matrix powder may range from 1 to 30% by weight of the overall weight of the blended powders.

Variations of the present projectile are depicted in FIGS. 2-8. In each depicted variant, the core 18 of the projectile 10 is frangible to the extent that when the projectile strikes a solid, semi-solid, or hydraulic target, the projectile commences disintegration into individual particulates (both powder particulates and jacket particulates) proximate the leading end 16 of the projectile and promulgates along the length of the projectile in a direction toward the trailing end 14 of the projectile.

At the outset and by way of example, it will be recognized that a projectile fired from 30-06 caliber rifle having a 1 in 10 twist will exit the rifle muzzle at about 2900 ft/sec and will rotate about its longitudinal centerline at about 208,000 rpm over a distance of at least 200 yards, for example. At this velocity and rate of rotation, disintegration of the projectile upon striking a target will occur over a period of time measured in nanoseconds. Accordingly, it is further to be recognized that the total disintegration discussed herein takes place over a time period of a few nanoseconds. Irrespective of this time factor, the present inventor has found that the alteration of the disintegration of the projectile along its length as provided by the present invention can be varied over a wide range of values by a wide range of techniques employing a disintegration limiter factor, to produce dramatic terminal ballistics upon the projectile striking a target, such as a standard gel block commonly employed in the industry for visually demonstrating the terminal ballistics of a projectile fired from a gun.

A typical frangible projectile of the prior art is depicted in FIG. 1 and includes a cup-shaped jacket, commonly formed of a soft metal and having a closed trailing end 14 and an open leading end 16. Housed within the jacket is a core 18 formed from a powder 20, commonly a blend of metal powders which have been compacted within a die into a self-supporting compact. Commonly, the open leading end of the jacket is at least partially closed about the leading end of the core. As described this closure may include defining employing an ogive 22 on the leading end of the projectile. Also commonly, the leading end of the projectile may include a meplat cavity 26.

With reference to FIGS. 2-5, one embodiment of a frangible projectile 10 embodying various aspects of the present invention, comprises a cup-shaped jacket 12, which is closed at its trailing end 14 and open at its leading end 16. In FIGS. 2-7, the projectile is depicted in an incomplete form at its leading end in particular inasmuch as the Figures are intended to depict those features which are paramount to the present invention. In each of FIGS. 2-5, the jacket includes a powder-based core 18 as described hereinabove.

With further reference to FIG. 2 it will be noted that the thickness of the jacket wall 28 proximate the trailing end 14 of the jacket is materially thicker than the wall thickness of the jacket proximate the leading end of the jacket. In this embodiment, when the projectile is fired from a gun having a rifled barrel, the outer surface 30 of the jacket is marked with the pattern of the rifling. When the projectile strikes a solid, semi-solid or a hydraulic target, such as the body of an animal, disintegration of the core and jacket commences at the leading end of the projectile and propagates toward and through the trailing end of the projectile. The commencement of the thickening of the wall of the jacket at a location 24 approximately midway between the leading and trailing ends of the jacket initiates the limiter factor of this embodiment. By reason of the greater (increasing) wall thickness of the jacket proximate the trailing end of the jacket, deterrence of the disintegration of the projectile begins upon the propagation of the disintegration reaching this limiter factor. Deterrence of the disintegration progress along the length of the projectile continues to increase with the increase in wall thickness of the jacket. Accordingly, when the disintegration of the projectile has progressed to the thickest wall section of the jacket proximate the trailing end of the projectile, such disintegration fails to disintegrate at least a portion 32 of the jacket proximate the trailing end of the jacket, leaving intact such portion 32 of the jacket, thereby preserving the rifling markings on the outer surface 34 of this intact portion of the trailing end of the projectile. Notably, in this embodiment of the present invention, the disintegration of the projectile is not abruptly halted. Rather, the progression and intensity of disintegration of the projectile decreases as a function of the increasing wall thickness of the jacket resulting in a portion of the jacket proximate the trailing end of the projectile remaining intact and therefore recoverable for examination of the rifling markings on the outer surface thereof.

In this embodiment, the increase in the wall thickness of the jacket may commence at a location 24 about midway between the leading and trailing ends of the jacket, and preferably at a location between the trailing end of the jacket and the midway location 24 between the leading and trailing ends of the jacket. In one embodiment, the wall thickness of the jacket is gradually increased from a minimum wall thickness proximate the midpoint between the leading and trailing ends of the projectile, to a maximum wall thickness proximate the trailing end of the jacket. In one embodiment the wall thickness of the jacket proximate the trailing end of the projectile may be about twice the wall thickness of the jacket at approximately the midpoint between the leading and trailing ends of the jacket.

With reference to FIG. 3, in a further embodiment of the present invention, the core-bearing jacket is provided with a circumferential groove, i.e., a cannelure 36, in the outer surface 30 of the jacket at a location where it is desired that the disintegration of the projectile along the length of the jacket diminishes relatively abruptly, even to the extent that the lower portion 41 of the jacket nearest the trailing end of the projectile is separated unto itself. At this point, the upper portion 43 of the jacket and core nearest the leading end of the projectile is essentially completely disintegrated. Disintegration of the lower portion 41 of the projectile may be halted completely or it may continue at a lesser intensity and speed of propagation by reason of the limiter factor introduced by the presence of the cannelure. The continuation of the disintegration action may serve to effect some disintegration of the lower portion of the projectile but at the same time, the intensity and speed of propagation of the disintegration has reduced to the extent that at least one portion of the jacket proximate the trailing end of the projectile remains intact and recoverable following impact of the projectile on a target. In the depicted embodiment of FIG. 3, the cannulure defines the limiter factor of this embodiment of the present invention. It will be recognized that location of the cannelure along the length of the projectile can be employed to select the implementation of the limiter factor of the projectile to suit a given projectile designed for a given application. For example, locating the cannelure nearer or further away from the trailing end of the projectile may be employed as a means to produce more or less disintegration of that portion of the projectile proximate the trailing end of the projectile when the projectile strikes a target. That is, the proximity of the cannelure limiter factor to the trailing end of the projectile determines the intensity and rate of progression of the disintegration front along the length of the projectile in that region of the projectile between the location of the cannelure and the trailing end of the projectile. For example, the closer the cannelure is to the trailing end of the projectile, the smaller will be the size of the particulates of the jacket upon the ultimate completion of the disintegration action of the projectile. Thus, desirably, the location of the cannelure along the length of the projectile is proximate the midpoint between the leading and trailing ends of the projectile.

With reference to FIG. 4, in a further embodiment of the present invention, there are disposed two cores 18 and 18′ within a single jacket. In this embodiment, the cores are separated by a disc 44 disposed in a plane substantially perpendicular to the longitudinal centerline 47 of the projectile and between the cores at a location about midway between the leading and trailing ends of the jacket. In this embodiment, disintegration occurs generally in two phases, the first phase involving disintegration of that core 18 nearest the leading end of the jacket, including dislocation and separation of the disc 44 from the projectile. Once the disintegration of the first phase reaches the disc, the disc no longer has support within the jacket, is impelled clear of or generally outside of, the disintegration front and therefore may remain substantially intact. However, in this embodiment of the present invention, the presence of the disc effectively halts further disintegration of the trailing end of the projectile, so that the portion of the core between the location of the disc and the trailing end of the projectile breaks away as a fee intact entity which may be recovered for analysis.

Another embodiment of the present invention is depicted in FIG. 5 and includes a jacket having an internal circumferential ledge 40 defined in the inner surface of the jacket wall proximate the trailing end of the projectile. In this embodiment, the ledge defines a limiter factor whereby disintegration of the projectile progressing from the leading end of the projectile, is lessened with respect to its rate of progression and its intensity of disintegration at the circumferential ledge. Upon the impact of the projectile with a target, this alteration of the disintegration leaves that section 50 of the jacket between the location of the ledge 40 and the trailing end of the projectile sufficiently intact as permits identification of the rifling pattern on the outer surface of this section of the jacket. FIG. 12 schematically represents a projectile as depicted in FIG. 5, but including a disc 80 embedded within the core at the location of the circumferential shoulder internally of the jacket proximate the midway point between the leading and trailing ends of the projectile. The disc 80 may be formed from a metallic material, a polymer material or other material suitable for developing a demarcation zone within the core at the location of the disc. Thus this disc becomes the delimiter factor in this embodiment.

FIG. 6 depicts another embodiment of the present invention which employs multiple cores 18 and 18′ stacked upon each other within the jacket. In this embodiment, that core 18′ adjacent the trailing end 14 of the projectile is provided with a projection 48 extending away from the leading end of the core.18′. This projection is essentially coincident with the longitudinal centerline 47′ of the projectile and is encircled by a soft metal, or like, ring 51 with the outboard end 52 of the projection being received within a blind bore 54 defined in the trailing end 56 of that core 18 most near the leading end 16 of the projectile. There is no jacket employed in the projectile depicted in FIG. 6. Rather, the projectile is self-supporting.

In this embodiment, the outer diameter of the ring is chosen to be slightly greater than the outer diameter of the projectile so that as the projectile passes through the rifle barrel, the outer circumferential surface of the ring is imprinted with the rifling markings of the barrel.

In this embodiment of FIG. 6, disintegration of the projectile is initiated at the leading end 16 of the projectile and propogates along the length of the projectile. This disintegration is temporarily abated due to the limiter factor arising at the location of the ring 51 and the joinder of the stacked cores 18 and 18′. Thereupon the ring, escapes the disintegration action intact and available for recovery from the target for analysis, etc. Following escape of the ring, the disintegration of the remaining core 18′ of the projectile continues to completion.

In FIG. 7 there is depicted a still further embodiment of the present invention wherein there are employed multiple self-supporting cores 18 and 18′, which are physically coupled to one another by a projection 48 extending from the leading end of the core 18′ and received within a blind bore in the trailing end of the core 18. No jacket is employed in this embodiment.

In this embodiment, that end of the core 18′ adjacent the trailing end of the projectile is provided with a cup-shaped cap 60 of soft metal, tin for example, which overwraps the trailing end of the projectile and extends therefrom up and about the outer surface of a substantial portion of the core 18′. The outer surface 61 of that portion of the cap which surrounds the core 18′ becomes imprinted with the rifling markings of the gun barrel from which this projectile is fired.

In this embodiment of the present invention, there are two limiter factors, the first being the junction 63 of the two cores 18 and 18′ and the second being the rim 64 of the cap fitted over the trailing end of the projectile. When the projectile of this embodiment strikes a target and disintegrates, the result is a flattening out of the cap, but without disruption of the rifling pattern on the outer surface of the cap so that the cap remains intact to the extent needed for identification of the rifling markings on the cap upon recovery of the intact cap from the target.

The further embodiment of the present invention depicted in FIG. 8, is substantially identical to the projectile depicted in FIG. 7 with the exception that the cap of FIG. 7 has been eliminated and the outer surface of the projectile has been provided with at least one, and preferably multiple, elongated metallic flat strip 62 which extends along the length of the projectile. As the projectile of this embodiment passes through a rifled gun barrel, the flat strip takes on the rifling markings of the barrel. Upon this projectile striking a target and commencement of the disintegration of the projectile, the limiter factor provided by the juncture of the two cores serves to at least dislodge one or more of the flat strips intact, thereby making these marked strips available for recovery from the target for analysis. Concomitally, each of the flat strips provides individual limiter factors which may abate the rate of progression and/or intensity of disintegration of the propagating disintegration action of the projectile.

FIG. 10 schematically depicts a typical intact portion of a projectile, commonly a portion of a jacket, cap, flat strip, ring, or like portion 65 of a projectile which has been recovered from a target and showing typical rifling markings on the portion.

FIG. 9 depicts a round of gun ammunition including a case fitted with a primer 74 and a projectile disposed in the leading end of the case. The depicted projectile of FIG. 9 shows the leading end of the projectile after closing of such leading end employing an ogive defined on the leading end of the projectile.

FIG. 11 schematically depicts the disintegration of a projectile of the present invention upon such projectile being fired into a gel block 70 as is well known in the art for observing certain terminal ballistics of a fired projectile upon it striking a target (the gel block in this instance). From FIG. 11 it will be noted that the projectile enters the gel block for a relatively short distance and thereupon commences disintegrating into individual powder particulates. As the elements of the projectile travel deeper into the gel block, the disintegration propogates along the length of the projectile and, in the present instance, at least one portion 65, and commonly multiple portions, of the projectile remain intact and available for recovery from the target for analysis. Whereas herein reference is made to recovery of an intact portion of the projectile from a target, it will be recognized that such intact portion may “miss” a given target but will be captured in some medium which is adjacent the actual target. Under these circumstances, the intact portion of the projectile is recoverable from such adjacent medium and the term “target” is to be deemed to include such adjacent medium.

Whereas the term “gun” has been employed herein for convenience purposes, it is to be understood that the projectile of the present invention most commonly is of the type which is suitable for being fired from a rifle or a pistol having a barrel which includes rifling interiorly of the barrel.

While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the invention to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept. For example, It will be understood by one skilled in the art that the projectile of FIGS. 6, 7 and 8 which do not include a jacket, as needed or best suited, may be of a non-abrasive powder or they may be individually plated with a non-abrasive coating to avoid abrasion of the rifling of the gun by the projectiles when they are fired from a gun. In one instance, the plating itself may be sufficient thick as to take on the rifling markings of the barrel of the gun from which the projectile was fired and to be recoverable from the target. 

1. An ammunition projectile adapted to be fired from a gun having a rifled barrel comprising at least one frangible powder-based core having a leading end and a trailing end and at least one portion of the projectile capable of being marked by the rifling of the barrel of the gun from which the projectile is fired, said core disintegrating into individual particulates upon the projectile striking a target, said disintegration commencing at the leading end of the projectile and propagating along the length of the projectile, at least one limiter factor disposed along the length of the projectile in the path of the propagating disintegration of the projectile, said limiter factor at least momentarily abating said propagation of said disintegration whereby at least said at least one portion of the projectile which is capable of being marked by the rifling of the barrel of the gun from which the projectile is fired becoming separated from the projectile intact and recoverable for analysis.
 2. The ammunition projectile of the claim 1 wherein said at least one core comprises at least one powdered metal compacted into a self-supporting compact.
 3. The ammunition projectile of claim 2 wherein said at least one core comprises at least first and second metal powders and a matrix comprising a polymeric material.
 4. The ammunition projectile of claim 1 where said projectile comprises at least two individual cores disposed in stacked relationship to one another.
 5. The ammunition projectile of claim 4 wherein said at least two individual cores are housed within a cup-shaped jacket.
 6. The ammunition projectile of claim 1 wherein said limiter factor comprises at least one of (a) a jacket having a leading end and a trailing end and is of a materially thicker wall thickness from a location about midway between the leading and trailing ends of the jacket and the trailing end of the jacket, (b) a jacket having a cannelure defined about the outer circumference of said jacket at a location between the leading and trailing ends of the jacket, (c) a jacket having at least two cores disposed therein in stacked relationship to one another, and a disc interposed between adjacent ones of said at least two cores, (d) a jacket having a leading first end and a trailing second end and a internal circumferential shoulder dividing said first and said second ends into first and second portions, said second portion having a materially greater wall thickness than the wall thickness of said first portion, (e) first and second compacted powder based cores disposed in stacked relationship to one another, said first core including a trailing end having a blind bore defined therein and said second core including a leading end and a projection projecting from said leading end and adapted to be snugly engaged within said blind bore, (f) first and second compacted powder based cores disposed in stacked relationship to one another, and a ring of metallic material interposed between the adjacent ends of said stacked cores, a projection extending from one of said adjacent ends in the direction of the other of said cores, said ring encircling said projection, (g) first and second compacted powder based cores disposed in stacked relationship to one another, said first core including a trailing end having a blind bore defined therein and said second core including a leading end and a projection projecting from said leading end and adapted to be snugly engaged within said blind bore, said second core having a trailing end and a cup-shaped cap overlying said trailing end and extending partway along the outer surface of said second core in a direction toward said first core, (h) first and second compacted powder based cores disposed in stacked relationship to one another, said first core including a trailing end having a blind bore defined therein and said second core including a leading end and a projection projecting from said leading end and adapted to be snugly engaged within said blind bore, and including at least one elongated strip of a metallic material mounted on the outer surface of said cores and extending substantially along the length of said stacked cores. and, (i) a jacket having a leading first end and a trailing second end and an internal circumferential shoulder dividing said first and said second ends into first and second portions, said second portion having a materially greater wall thickness than the wall thickness of said first portion and including a substantially rigid disc embedded within the core at the location of the internal circumferential shoulder. 